Research On Arctic Transport Ship Ice Load And Ice-breaking Performance

Most of icebreakers in world were built in northern Europe, Russia, and U.S.A., etc. China today has not got enough experience on designing or constructing professional polar icebreakers. But nowadays, ice in polar area is abating in a steady speed, so countries in Europe, North America and other lands have opened up arctic shipping lines. Currently routes of Arctic Ocean only remain in northern summer season, while flotillas are mainly formed by LNG vessels and oil tankers. Ships sailing in Polar Region are always built with thick shell plates, equipped with high power engines and which also has a higher waterline coefficients. In addition, as a method of reducing cost, modifying non-polar ship with ice preventing structures is also acceptable to ship companies.Either professional icebreakers or ice transporters, severe challenges brought by sea ice are unable to avoid. Once accidents occurred, not only ship owners and sailors will suffer huge losses, but also more critically, it is a great disaster to polar environment. So people must pay more attention in polar ships design and construction to raise the safety. In this case, speed characteristics and economical index are the secondary factor.At first, this paper introduced the classification, structure and properties of sea ice briefly, and made some comparisons with the related current theory. As former theory did, freshwater ice is used as research object and established isotropic visco-plastic finite element numerical model by LSDYNA. Then made comparisons between simulation results and ISO recommended pressure-area curve and ice impact experiments results respectively, to evaluate the accuracy of numerical model.Secondly, relationship between icebreaking resistance and different contact angles were briefly demonstrated. There were several conclusions obtained. One is that resistance declined with the decreasing of surface to bow angle in vertical direction. The other is when bow angle in waterline plane is about 90°, there is the least forwarding resistance. Besides, two kinds of typical structure were also compared on icebreaking mechanism and ice damage effect.Finally, by analyzing an ordinary ship’s bow and flat ice damage characteristics when ship-ice collision occurs, results were drawn. Vulnerable parts of the bow were mainly distributed in the region of two sides of the stem and its adjacent behind area. In this area, damage was characterized as cross cut damage and compression damage. A recommendation was made for the further design or modification, which transverse frame type would be better in ship-ice collision.